The present invention relates to document processing systems, and is particularly directed to a method of processing documents moving along a transport path of a document processing system, such as a check processing system, and an apparatus therefor.
There are a number of known arrangements of components for detecting a double-item feed condition in a document processing system having a transport path along which documents are movable. One known arrangement of components includes a number of light emitting diodes located on one side of the transport path and a corresponding number of phototransistors located on the other side of the transport path. Each phototransistor senses the amount of light transmitted through a document moving along the transport path and provides a sensor output signal indicative of the amount of transmitted light. If a single document is fed along the transport path, then the sensor output signal is within a predetermined range of values to indicate a normal feed condition. If overlapping multiple documents are fed along the transport path, then the sensor output signal is outside the predetermined range of values which would indicate a multiple-item feed condition.
A disadvantage in using this known arrangement of components is the inability to distinguish between detection of an actual multiple-item feed condition and detection of a "carrier" document. A carrier document is simply an envelope into which a damaged document can be placed to transport the damaged document along the transport path. The above-described arrangement of components may detect the presence of a carrier document as a multiple-item feed condition. Since a carrier document is not an actual multiple-feed condition, the result is a false indication of a multiple-feed condition. This false indication of a multiple-feed condition may cause the carrier document to be rejected. To avoid rejection of the carrier document, an operator may need to manually override the sensor output signal so that the carrier document can be processed as a normal feed condition along the transport path.